MONOGRAPH OF THE GENUS STROPIIIA. 
170 
There is one remarkable character in this species which is found 
in all the forms and one which is, as far as I have examined, peculiar 
to this Strophia, although 1 shall expect to find it occurring in others. 
That is a swollen ridge which, beginning back of the central tooth, 
winds about the column about once its width from it, thus leaving a 
furrow between it and the column, extends, gradually lessening in size, 
and it is lost in the third whirl. This ridge was once the resting 
place of the central tooth, and in one place, in one of the specimens 
examined, a tubercle still remains on at the partition in the lower portion 
of the second whirl, See Fig. 61, A, 
being a section of a specimen of S. 
eximea, and the tubercle may be seen 
in the second whirl. This elevated 
ridge is no thicker than the other 
portion of the floor of the whirls, conse- 
quently has a corresponding hollow 
beneath. Nothing of the kind appears 
in the apparently closely-allied species 
S. agrestina, where the floor of the 
whirls is perfectly simple. See Fig. 
61, B, where I have given a section a, section or S. eximea. C. cross section 
„ 0 ~ . . of same. B, Section of S. agrestina. 
ol S. agrestma. C, is a cross-section 
of the top whirl of S. eximea, showing 
the central tooth and beginning of the ridge. 
HABITS AND DISTRIBUTION. 
All that I can give under this heading is the fact, that the speci- 
mens from which the above description was made were procured by 
Mr. Curtiss, in Nassau, from a creole who brought them from Cat 
Island. 
The species is, however, not uncommon in collections, often 
labelled as Pupa cr Strophia martensi or martensiana. 
54 STROPHIA AGRESTINA Novo. 
Grass Strophia. 
Fig. 60. A, front view, B, side view, of type. C, margin, Form No. 3. 
DESCRIPTION. 
Sp. Ch. Size, small. Shell, very thin and fragile. Striations 
Fig. 61. 
B A 
